1. Field of the Invention
The invention is directed to a strain gage weighing scale of the type generally found in home bathrooms and which has supporting feet, usually one at each corner, in a substantially square scale. To this type scale, the individual foot structure is improved so that each foot contains one or more strain gages in a combination such that the overall scale has an individual weighing structure at each foot as opposed to the common relatively movable or telescoping load and base platforms with a single beam structure therein. The result is an overall scale that is very thin or low profile to improve over the more bulky scales generally used.
2. Description of the Prior Art
In the common household weighing scales particularly of the bathroom type, it is customary to house weighing structure in a generally square base and to use a movable upper platform cupped over the base and supported on common beam structure and spring within. A convenient dial or digital readout is suitably calibrated to indicate the weight as, for example, in pounds. Such a general type scale is shown in U.S. Pat. No. 4,173,263 of common assignment and the references therein. These are generally the most common and least expensive of the home bathroom type scale. More complex scales use different means to balance the weight such as beams connected to load cells which produce electrical signals that are converted to digital readouts of weight applied as shown in U.S. Pat. No. 3,831,687. Any number of plain load cells also may be placed under platforms as shown in U.S. Pat. No. 2,488,347. Both latter types may use strain gages whose resistance changes as they are stressed and the resulting resistance used by balancing in a Wheatstone bridge or by calibrating any conventional summing circuit to directly read weight--both being strain gage applications that will directly read in weight. Further, scales using integrated circuitry have been designed with responsive tranducers electrically connected to indicate weight. Temperature changes affect the supporting transducers and produce changes in transducer operation particularly in terms of the zero calibration reading. A typical transducer scale of this type is disclosed in now U.S. Pat. No. 4,355,692 dated Oct. 26, 1982 of common assignment. An improved invention to provide a zero calibration and zero error correction arrangement especially helpful in the scale of the type of said '749 application is shown in U.S. Pat. No. 4,313,510 of common assignment.
Generally, the scales thus described may be considered larger and more bulky than desired in some uses. The present invention is directed to an improvement of a strain gage weighing scale using special plural spaced foot structures supporting a low platform, each individual foot structure comprising a sandwich construction that results in an overall combination that is thin or very low profile for a more pleasing and inexpensive bathroom type scale.